To date we know of several embodiments of incubators such as the one disclosed in U.S. Pat. No. 3,543,726 which relates to an egg incubator having a generally circular horizontal vented support platform at a position slightly above a base, and a plurality of spokes disposed in a circular ring with said spokes radiating from the center of the platform. Said incubator is provided with a circular cover which is removably disposed on the base for rotational movement relative to the base, and with means for transmitting rotary motion of the cover to said ring of spokes and thence to eggs disposed on the platform between said spokes in order to turn the egs without opening the cover.
U.S. Pat. No. 3,699,075 discloses an automatic egg turner for incubator having a drive motor which drives an output shaft having a cam thereon, and a crank arm provided on said output shaft, which is connected to the egg grid of an incubator to move said grid from one position to another each time the output shaft is rotated 180.degree..
U.S. Pat. No. 3,783,832 is related to an automatic egg incubator in which a rack supports the eggs in a row with a movable grid above the rack extending between the eggs. The grid is moved periodically by a motor to turn the eggs. A transparent dome-like cover extending over the eggs supports a fan and a heater, while a plate supported by the cover directs the air downwardly around the periphery of the rack and upwardly towards the centrally supported fan. This incubator also includes a humidifier water supply fountain.
The embodiments above discussed are apparently similar to the incubator object of the present invention, but they present serious deficiences in the egg turning system, in the control of the heat and in the control of the circulation of the air that carries the oxygen and other gases which are necessary for the correct incubation and hatching of the eggs.
In incubators of this type the system used for rotating the eggs, as the ones disclosed in U.S. Pat. Nos. 3,543,726; 3,669,075 and 3,783,832 are deficient since usually the eggs are dragged over a wire mesh by activating a plastic ring that supports a radial wire strip and that drags the eggs along with it when it turns. With this turning system the egg is sometimes dragged along without being turned or rotated and the corresponding segment also sometimes tends to remain crosswise. In incubators of this type, cleaning and sanitation is impossible because there are intercommunicated spaces to which there is no access for cleaning.
The incubators known to date use a resistance light bulb or a resistor as a heat source, which is mounted on a plastic baffle plate, and the thermostat is placed on this baffle at the same level of the heat source. The result of this arrangement is that the thermostat is very close to and practically in direct contact with the incandescent thermic resistance, which makes the thermostat to actuate deficiently and with a greater risk of damage. Moreover, the location of the thermostat keeps same distanced from the precise place where the optimal temperature must be regulated for an optimal incubation process.
The most important of all these problems concerns the air circulation, since the known incubators do not control neither the admission or the exit of air, and thus it is impossible to regulate the humidity and the balance of gases required for a good incubation.